Lighting device



May 19, 1942. c. H. BRAsEL-TON 2,283,352

LIGHTING DEVICE Filed oct. 15, 195o s sheets-sheet 1 May 19, 942- c. H. BRAsELToN 2 2,283,352

LIGHTING' DEVICE Filed Oct. l5, 1930 5 SheetS--Shee'l 2 May 19, 1942 c. H. BRASELTON 2,283,352

LIGHTING DEVIG E Filed Oct. l5, 1930 3 ShetS-Sheet 3 IN VENT 0R l Patented May 142 LIGn'rmG nvlcE chester n. raselton, New York, N. r., assignor, by mesne assignments, to Sirian Wire and Contact Company, Newark, N. J., a corporation of Delaware Application October 15, 1930, Serial No. 488,733

i 17 Claims. (Cl. 176-122) This invention relates to electric lamps and particularly to that type of lamp which makes use of the passage of an electronic stream.`

through space for its operation. s,

One of the objects of the invention is 'to provide a lamp in which a refractory body is bombarded by a stream of directed land controlled electrons. f g

Another object of th`"invention is to provide an electric lamp in which a cathode surface is heated to electron emitting temperature in the presence of an ionized gas and bombards a refractory body heating it to incandesence by said bombardment.I

Another object of the invention is to provide an electric lamp in which the temperature of the light giving element is raised toa higher point than possible where such element carries the current for operating the lamp.

Other objects of the invention and objects relating particularly to the method of constructing and assembling the various parts will be apparent as the description of the invention proceeds'.`

Several embodiments of the invention have Fig. 4 is a side elevation of a lamp illustrating a still further modification;

invention is shown as comprising an envelope IIJ I having the usual press II formed integral therewith and for the purpose of supporting thevarious elements. A cathode I2, preferably formed as a cylindrical shell out of a refractory metal such as tungsten, molybdenum, tantalum, or nichrome, may be supported by means of a short connecting rod I3 which may be welded to a support rod I4 sealed in the press I I. The cathode I2 may be filled with an insulating material I5 whichmay be any suitable material capable .25 been illustrated in the accompanying drawings Fig. 5 is a side elevation of another modiiication of the invention;

Figs. 6 and 7 are modified forms of the inner coils shown in the construction of Fig. 5;

Fig. 8 is an elevation of a still further modification of theinvention;

Fig. 9 is an enlargement of the ,upper end vo1' the construction of Fig. 8;

Fig. 10 is an elevation showing another embodiment of the invention;

Fig. 11 is an elevation showing a still further modified form of the invention;

Fig. 12 is'a longitudinal sectional view of a modified form of the construction shown in Figride thereof, may be place Referring now morevspecically to Fig. 1 the 55 of standing a high temperature and permitting .degasication A lamentary resistance wire I6 may be embedded in the insulating material I5 with its lower end connected to the support rod I4 and its upper end connected to a support rod I1 which may be bent outwardly and downwardly, extendingsubstantially parallel to the cathode but spaced therefrom and sealed in the press II. The cathode cylinder may also be coated with electron emitting material I8 which maybe any of the well known materials used for that purpose, such as the oxides of the alkali earth metal group or mixtures of such oxides held together upon the cathode with a suitable binder.

.A coil I9 of refractory wire, preferably tungsten, may be placed around the cathode I2 but having a large enough diameter to be spaced therefrom and the upper end of this coil may be connected to the support rod I1 while the lower end may be connected to a third support rod 20 which may be sealed in the press II.

The envelope I0 may be filled with an ionizable gas, preferably'one of the monatomic gases,`such as neon, argon, helium, krypton, or xenon, or mixtures 0f such gases, at a pressure of in the neighborhood of 200 mm. of mercury. ,f A trace of a metal vapor or vapors may be added to the gas if desired for color effects or to increase the conductivity thereof. These vapors may be vausual manner of a pressed metal cup and supported by means of a wire 22 upon one of the support rods, as the rod I .in Fig. 1. A small quantity of a salt ofthe me al, such as the chloin the container 2| with a small piece of calcium or magnesium and when the container 2I is heated to a high enough temperature the calcium or magnesium will combine with the chloride of the metal forming calcium or magnesium chloride and liberating the free metal which will condense on the walls `of the .bulb and other parts to be vaporized again when heated in use.

Lead-in wires. 23 and 24 may be connected rei spectively to the support rods Il and I4 for making the oxide connections to the bulb,

With the parts assembled as shown in Fig.-1

the envelope I8 may be connected to an exhaust pump and an ove` placed over it to raise the temperature of the entire lamp to between 350 and 400 C. A current may be run through the filament at this. time to heat it slightly so as to expel the gases therein and the pump then withdraws the gases as they are liberated. When no more gases are apparent in the bulb as is evidenced by a lack of fluorescence when high tensionj/ current is directed against the walls of the bulb from an induction coil, the current through the filament may be increased to raise the temperature thereof to approximately 800 C. to drive out'the binder from the electron emitting material on the outer surface of the cathode and other occluded gases which may be present. When no more gases are again found in the bulb the oven may be raised and the filament current increased to raise the temperature to slightly less than 1200 C., the pump being connected all this time to remove the gases driven ofi.

When no more gases appear in the bulb the filament current may be turned off and thepump disconnected and a slight amount of an inert gas, such as neon, having a pressure of about .5 mm. admitted to the bulb and the filament current turned on again and increased gradually.

Spots of localized discharge will then appear on the parts of the bulb and will gradually spread until a diffused glow completely fills the bulb. This appears to activate the electron emitting material and the process -should be continued until the glow completely fills the bulb which should take less than ten minutes.

If white discharge spots appear on the cathode or other parts of the light it is an indication that there are more vapors or gases within the bulb and the pump should be again connected and the gases withdrawn and the process of activation repeated.

When the activation is completed the filament current may be raised for a moment to approximately 1400 C. and the gases pumped out again to remove any undesirable gases which may have been driven oil during the activation process. At this time a high vacuum of in the neighborhood of .5 micron is preferably obtained. The vacuum pump may then be shut oil and theiilament current turned H and about 50 mm. of neon and 150 mm. of argon admitted into the bulb after which the bulb may be sealed oil.

If the metal vapors are to be introduced into the bulb as stated above the container 2|,E may be bombarded externally after sealing oil to liberate the metal vapor or if the metal vapors are not used it may be desirable to flash some magnesium in the same manner to clean up the gases in the bulb.`

When the bulb as described is connected across a light circuit current will flow through the leadin wire 23, the support r'od I1. the filament I8, the support I4, and will pass out through the lead-in wire 24. This will energize the filament I8 causing it to heat the insulation material and the cathode I2 and raise the temperature thereof until the electron emitting material reaches the emission temperature. Inasmuch as the cathode I2 is electrically connected by means of the rod I3 to the support rod I4 which forms one side of the circuit.. and the coil I9 is electrically connected to the rod I1 or to the opposite side of the circuit the potential between the coil I8 and the cathode I2 will be the line potential and a stream of `electrons will therefore leave the cathode and bombard the coil I9 increasing the temperature thereof until it radiates light.

In Fig. 2 a modified form of the cathode is shown wherein a coil I2a of refractory metal is closely wound on the insulating core instead of a metal shell.

In Fig. 3 a cathode 28 similar to the cathode I2 of Fig. 1 and coated with electron emitting material 28 may be supported upon a rod 21 which is sealed in the press II by means of a strap 28 at its upper end and a strap 29 at its lower end. A hairpin coiled filament 30 may be embedded in the insulating material 3| which extends through the cathode 28 while the ends thereof may be connected at vthe lower end of the cathode to two support wires 32 and 33. A connector 34 may connect the rod 33 with the rod 21 so that the cathode is electrically connected to one side of the heating coil. A large coil 35 of refractory metal 'such as tungsten may be supported upon a rod 38 which may extend parallel with the cathode and be sealed in the 'press in the usual manner. The support rod 38 may be connected to the support rod 32 by means of a short support rod 31 so that the coil 38 is connected to the opposite side of the heater circuit. With this construction a-greter resistance may be made per unit length of cathode inasmuch as two lengths of the coilextend through the cathode.

Inasmuch as the electrons move from a negative body to a more positive one the electron stream in the construction of Figs. 1 and 3will operate only on one-half of an alternating current cycle and in order to make the lamp use both halves of the cycle the construction of Fig. 4 may be used. In this construction a pair of cathodes 38 and 39 are mounted in parallel relation and spaced from each other upon a central support rod 40 by means oi' straps 4| and 42 which pass around the upper and lower ends respectively of the cathodes and are welded-to the support rod 40. A single coiled filament 43 may extend up through the cathode 38, and be attached to a connector 44 at the top thereof which maybe welded to the upper end of the rod 48 and extend over the top of the cathode 39. An-

other single coiled filament 45 may extend those already described and illled with an insulating material -in which the filament 43 and 45 are embedded. A coil of heavy tungsten wire 48 may surround the cathode 38 ,while a coil 49 may surround the cathode '39 in a manner similarly to what has already been described. 'I'he upper and lower ends of the coil 43 may be supported upon a support Vrocl I0 while the upper and lower ends of the coil 49 may be supported upon a support rcd 8| as indicated. The coils should be made of heavy enough wire to maintain their position spaced from the cathodes 38 and 39.

In this construction it will be cathodes through the support rod 40 are connected to the midpoint of the double filament 43 'evident that thev I, wires 54 and 55 may also be connected together to connect the coils 48 and 49 to opposite sidesl of the circuit. v

With this construction a potential difference between either cathode and its adjacent coil will be substantially one-half of the potential across the entire circuit and as both cathodes are connected to the midpoint of thel lament the cathodes will always be negative with respect to; one of the coils so that atleast one coil will always be bombarded which produces a uniform effect throughout both halves of the cycle.

While the tubular cathodes as shown in the foregoing construction are indicated as being lled with insulating material in which the filament is embedded, it is also possible to support the filament within the cathode without any insulation material so that the cathode will heat by radiation only from the filament.

In Fig. a furtheru modification of the construction is shown. Here a plurality of coils 56 and 51 of relatively heavy refractory Wire are mounted at their lower ends respectively upon support rods 58 and 59 which may be sealed in the press 60 and surrounded by the envelope 6|. The coils 56 and 51 may have a relatively large diameter and the upper ends Ythereof may be bent inwardly to form supports for two smaller coils 62 and 63 which extend down through the center of the coils 56 and 51 and are attached to a cross connecting member 64 which in turn may be welded to a support rod 65 sealed in the press 60. 'Ihus the small coils 62 and 63 are supported within the larger coils and spaced therefrom. Each of the coils 62 and 63 may be provided with a coating of electron emitting material which, as shown, is coated upon the individual turns of the coil.

Leading-in wires 66 and 61` may be connected respectively to support rods 58 and 59 so that when the lamp is connected across a lighting circuit the current flows through the leading-in wire 66, the support rod 58, the large diameter coil 56, the small coil 62, the connecting member 64, the small diameter coil 63, the larger diameter coil 51, the support rod 59, and out through the leading-in wire 61. 'Ihis energizes all of the coils although the small diameter coils will heat up to a high temperature due to the higherresistance and as soon as these small diameter coils become heated to the electron emitting temperature electrons will bombard the outer coils and 45 and that the coils 48 and 49 are connected wire is shown supported upon a rod 8| at the and raise the temperature thereof so that they become refractory and emit intense illumination. Y

The small diameter coils 62 and 63 may if desired be coated with electron emitting material -as indicated in Fig. 6 where the coil 68 is shown coated with electron emitting material 69, or the construction of Fig. 7 may be employed in which the coil 10 is provided with a core 1| of electron emitting material. The latter construction may be preferable inasmuch as the core inside of the coil helps to support it and will prevent it short circuiting against the outer coil. However, if desired, the filament itself may bemadeelectron emitting by makingit of thoriated tungsten which may be made by treating tungstic acid and thorium nitrate or a filament in which other coil 12 of resistance Wire is bent in the form of a the material rather than the coil as a coating electron emitting materials have been intimately. mixed with themetals may be used. Any of the constructions, however, will provide the same results in that the outer coils are bombarded by electrons and the` temperature thereof raised to radiating temperature.

A somewhat different embodiment of the invention is shown inv Fig. 8 in which a i'llamentary V, or hairpin, having the ends thereof attached to two support rods 13 and 14 which may be sealed in the press 15 of the lamp. A center support rod 16 may have a tungsten or other refractory Wire 11 welded to it which is provided at its upper end with a ring or loop 18 through which the filament 12 may extend to support the upper end of the filament. The wire 11 may be coated with electron emitting material 19 and in operation when this wire becomes heated it will emit electrons, inasmuch as it is attached to the midpoint-of the filament, to the sides of the V filament which are left uncoated, thereby bombarding the filament and raising the filament to a higher degree than it is raised by the current passing therethrough.

In Fig. 10 a coil 80 of fllamentary resistance top and a rod 82'at'the bottom thereof. This coil may be coated with electron emitting material in any of the manners already described. A rod 82 of refractory metal ,or other refractory material, such as carbon, may be supported at its upper end upon the rod 8| and at its lower end upon the support rod 83 provided for that purpose. The rod 82 is positioned substantially parallel to the axis of the coil and as it is connected to one end thereof it will be bombarded by electrons from the coil. raising the temperature thereof to a radiating temperature and thereby emitting light.

In Fig. 11 a modification of this construction lis shown in which the rod extends within the coil on the axis thereof. As shown, the rod 84 is attached to a support rod 85 which also forms the support rod for one end of the coil 86 the other end of which is attached to a support rod 81 which is, together with the rod 85,` sealed in the press 88. 'I'he rod 84 is mounted on the axis of the coil 86 and may be coated with electron emitting material, if desired, to bombard the coil, or the coil itself may be coated with electron emitting material as indicated in Fig. 12 where the coil 89 is provided with electron emitting material 90 and the rod 9| extends inside of the coil. However where the rod extends in the center of the coil it may be preferred to coat the rod with upon the coil may tend to interfere with the light thrown out from the rod. f

A further modification of the invention is -illustrated in Fig. 13 in which two relatively small diameter coils 92 and 83 are mounted in parallel relation to two coils 94 and 95. Support rods 96, 91, 98, and 99 sealed in the press |00 support respectively the coils 94,92, 93, and 95. A center support rod |0| may be sealed in the press |00 and may be provided with a glass bead |02 at the upper end thereof in which is sealed a connector |03 which supports and electrically connects the upper ends of the coils 94 and 9-3. A second connector |04 may be welded to the support rod |0| and may connect the upper end of the coils 92 and 95. 'Leading-in wires |04 and |05 may be connected to the support rods 96 and 99 respectively while leading-in wires |06 and 4 |01 may be connected respectively to the support rods 91 and 90. 'I'hese latter leading-in wiresI |09 and |01, may be connected together andl when s'o constructed current `will flow, in operation, through the leading-in wire |04, the support rod 96, the large diameter coil 94, the connector |03, the small diameter coil 99, the support rod 9B, the leading in wire |01, the leading in Wire 'aasasta'f in-simple series therewith, and an ionizable gas |09, the support rod 91, the small diameter coil l' 92, the connector` |04, the large diameter coil 95, the support rod 99, and out through the leading-in wire |00. At the center of each of the coils 92 and 93 I provide, respectively, electron emitting coatings |08 and |09which may extend a portion of the length and are preferably provided at the center or away from the support rods to prevent arcing across the high potential rods. Current flowing through the coils as mentioned raises the temperature of the ne wire coils 92 and 99 to a greater temperature thanv the outer coil. The electron emitting material 'tends to emit electrons when the temperature becomes high enough and, inasmuch as the larger surrounding said element and anode.

3. An electric lamp comprising an envelope, a coil of iilamentary resistance wire within said envelope, means togive said coil a high electron emissivity when said coil is energized by -a current of electricity, a second coil adjacent the4 first coil but spaced therefrom, means to connect said second con -m series with said nrt con,`l

and anionizable gas surrounding said coil.

4. An electric lamp comprising. an envelope, a coil of fllamentary resistance wire within said envelope, a second coil of refractory wire sur rounding said first coil, a coating of electron emitting material on said first coil to render said first coil electron emitting when a current-of-.

electricity is run therethrough, means to connect said coils in series, and an ionizable gas sunrounding said coils.

5. A negative glow lamp of the gaseous'conduction type comprising an enclosing envelope, a

' plurality of thermionically active electrodes diameter coils 94 and '95 having a relatively large difference in potential from the smaller diameter.

tendency is found to spread. the bombardment throughout the length of the filament or to overheat the filaments at the high potential ends.

In any of the constructions shown it is obvious that several elements may be provided either connected in series or in parallel and these elements may 'be positioned in any desirable manner within the envelope. Also while I have specifically referred to an ionized gas within the envelope it maybe preferred to operate some of the modifications of the invention with traces of the metal vapors such as mentioned above and it may also be desired to operate some of the constructions in a vacuum and I do not therefore desire to be limited to the use of an ionized gas. I have also referred to. certain specific pressures for the gases but it is to be understood that where a gas is used the pressure may be varied depending on the character of the discharge desired and the voltage used. Lowering the pressure tends to cause the discharge around the emitting element to expand.

Many other modifications of the invention may A be resorted to without departing from the spirit thereof, and I not therefore desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claim and secure by Letters Patent is:

l. In an electric lighting` device a tubular cathode, a coil of refractory wire around said cathode and spaced therefrom, electron emitting material in surface contact with said cathode, means to heat said cathode, means to give said coil a different potential from said cathode when a current isapplied to said device, and an ionizable gas surrounding said coil and cathode.

2. A lamp comprising ari envelope, an electron emitting element within said envelope, an anode spaced slightly from said element and connected therein and a grid located between said electrodes.

6. A negative glow lamp of the gaseous conduction type comprising an enclosing envelope, a plurality of thermionically active electrodes therein, a perforated grid located between said electrodes, said grid being in parallel electrical relationship with one of said electrodes.

7. An ultraviolet lamp comprising an enclosing envelope, an ionizable medium therein, said envelope having a press, a plurality of electrodes supported by said press, each of said electrodes including a heating element and a thermionically active material, the heating elements ofsaid electrodes being. in electrical series relationship,

and a grid located in the space between said electrodes. w

8. An ultraviolet lamp comprising an envelope, an ionizable medium therein, a plurality of thermionic electrodes and a grid also located therein, said electrodes being spaced from each other and supported by a press, said grid being located in the space between said electrodes, each of said electrodes including a hollow body having a thermionically active surface and a heaterelement, said heater elements being/connected in electrical series relationship, said grid also being supported by said press.

9. An ultraviolet lamp comprising an enclosing envelope, an ioniaable medium, a plurality of electrodes and a grid located therein, said electrodes being spaced from each other and supported by a press, each of said electrodes including a heater element and a thermionically active material, a grid located in the space between said electrodes, said grid being in electrical parallel relationship with one of said electrodes.

10. A direct current electric cathode-glow lamp, comprising a, translucid' bulb, a filling in said bulb consisting mainly of-at least one rare gas, a metal cathode in said bulb having a coating of the alkaline earth type, a resistance type heater for said cathode, means for energizing said heater, a wire anode in said bulb bent substantially into a helix surrounding and symmetricallydisposed with respect to the cathode and at a uniform distance from the latter and means for applying a potential difference between the two electrodes, said anode having a small total surface area with respect to the cathode area.

l1. A negative glow lamp of the gaseous conduction type comprising an enclosing envelope,

' relationship, and a grid located in the space between said electrodes.

13. A'gaseous ccnduction lamp comprising an envelope, an ionizable medium therein, a plurality of thermionic electrodes and a grid alsoV located therein, said electrodes being spaced from each other and supported by a press, said grid being located in the space between said electrodes, each of said electrodes including a hollow body having a thermionically active surface and a heater element, said heater elements being connected in electrical series relationship, said grid also being supported by said press.

` 14. A gaseous conduction lamp comprising an enclosing envelope, an ionizable medium there, in, said envelope having a press, a plurality of electrodes supported by said press each of said electrodes including a heating element and a thermionically active material, the heating elements of said electrodes being in electrical series relationship, and a plurality of apertured electrically conducting cylindrical grid elements completely surrounding said electrodes respective- 15. A gaseous conduction lamp comprising an envelope, an ionizable medium therein, a plurality of thermionic electrodes and a grid also located therein, said grid being formed as an apertured electrically conducting cylindrical element and completely surrounding at least one of said electrodes, said electrodes being spacedv from each other and supported by a press, said grid being located in the space between said electrodes, each of said electrodes including a hollow body having a thermionically active suriace and a heater element, said heater elements being connected in electrical-series relationship,

said grid also being supported by said press.

16. In an electric lighting device, dual tubular cathodes, a two-sectioned heater for said cathodes, each section of the heater being positioned within one of the cathodes and electrically insulated therefrom, means to connect the midpoint of the heater to one of said cathodes, a pair of anodes spaced from said cathodes, one of said anodes being connected to one end of said heater and the other anode being connected to the other end of the heater, and an ionizable gas surrounding the anodes, cathodes and heater.

17. In an electric lighting device a cathode, a coil of refractory wire adjacent said cathode and spaced therefrom, means to heat said cathode to electron emitting temperature, means to give said coil a diierent potential from the cathode when a current is applied to said device, and an ioniz- 'able gas surrounding said coil and cathode.

CHESTER H. BRASELTON. 

